GCN Circular 2991
Subject
GRB 050128: Swift XRT prompt afterglow position
Date
2005-01-28T09:17:28Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
L. A. Antonelli (INAF-OAR), S. Campana, G. Tagliaferri, C. Pagani, A.
Moretti, P. Romano, G. Chincarini (OAB), G. Cusumano, V. Mangano (ISAF/Palermo),
P. Giommi (ASI), D. N. Burrows, J. E. Hill, J. A. Kennea, J. Racusin,
J. A. Nousek (PSU), J. Osborne, K. Page, M. Goad, A. Beardmore,
A. Wells (U. Leicester), K. Mason (MSSL), N. White, N. Gehrels (NASA/GSFC),
report on behalf of the Swift XRT team:
The Swift BAT instrument detected an apparent burst at 04:20:04 UT on 2005
January 28. The spacecraft initiated a prompt automated slew and
observation sequence. The XRT began taking data on the burst at 2005-01-28
04:23:51 and continued until 2005-01-28 05:55:27. The XRT was in Photon
Counting mode performing calibration observations of PG1311+129 when the
burst occurred, and continued to collect data in Photon Counting mode
during the slew and after settling onto the BAT field. As a result, no
prompt XRT position was reported to the ground. However, analysis of the
XRT data shows a bright, rapidly fading point source at:
RA(J2000): 14 38 17.87
DEC(J2000): -34 45 56.6
These positions were processed through the ground pipeline and have an
estimated uncertainty of 8 arcseconds, dominated by systematic
uncertainties in the XRT boresight, which is not yet fully calibrated. We
note, however, that our final position for GRB050126 was 30 arcseconds from
the optical candidate (GCN 2985) in spite of our estimated uncertainty of 8
arcseconds.
The XRT count rate is 1.29+/-0.28 c/s (0.5-10 keV) in a 1745 s exposure,
which corresponds roughly to a 1 mCrab source.
The XRT is continuing to observe this burst when it is visible to the Swift
observatory.
[GCN OPS NOTE (28jan05): Per D.Burrows request, the authors G. Cusumano, V. Mangano
were added to the list.]